Rest and Postural Tremor

Phones only. Seated, eyes closed, the participant holds the phone in the palm with the forearm resting on the thigh (rest tremor), then in the outstretched hand, palm up (postural tremor), 15 seconds per hand, counting down out loud from a number shown before each test. A vibration marks the start and the end of each recording. The web preview shows the screens only.

Useful for frequent, remote tremor measurement in Parkinson's disease, essential tremor and medication studies, where change over repeated tests and differences between the hands matter.

Not a diagnostic test and not a replacement for a clinical tremor rating: correlations with the MDS-UPDRS tremor items ranged from .23 to .71 (Lipsmeier et al., 2022). The weight of a phone held in the outstretched hand affects the arm's movement, which may weaken postural-tremor measures (Kostikis et al., 2015). Beta: being checked on iOS and Android devices.

The defaults follow the rest and postural tremor tests of the Roche PD Mobile Application v2 (Lipsmeier et al., 2022): seated, eyes closed, the phone in the palm with the forearm on the thigh, then in the outstretched hand, counting down aloud from a number that changes each time, 15 s per hand. The palm faces up in the postural test as in the first version of the app (Lipsmeier et al., 2018). Plan repeated tests: Lipsmeier et al. summarized tests over 2 weeks.

• Tests: rest, postural or both (default both; Lipsmeier et al., 2022)
• Hands: both (default; Lipsmeier et al., 2022), left or right; which hand first (default left; not stated in the source)
• Seconds per test (default 15; Lipsmeier et al., 2022; the 2018 version recorded 30 s with the more affected hand)
• Count down aloud during the tests (default on; Lipsmeier et al., 2022), from a random number between 60 and 100 (the range is not stated in the source; Lipsmeier et al., 2018, counted down from 100)
• Seconds to get into position before the start vibration (default 5; no published value)
• Store each test's acceleration and rotation rate, about 65 KB per 15 s test (default on; no published value)
• Fixed: each recording starts 0.5 s after the start vibration (no published value); a recording with a gap of more than 0.5 s in the sensor data, or with the stop question open, is flagged and not scored (no published value)

• Log median squared energy per test and hand: the natural log of the median of ax² + ay² + az² (Lipsmeier et al., 2022), with gravity removed; also with gravity included, because the source does not say which it used
• Tremor power between 2 and 10 Hz, (m/s²)², and the dominant frequency per test and hand, from the magnitude of the acceleration, √(x² + y² + z²), high-passed at 2 Hz (Kassavetis et al., 2016)
• The larger of the two hands per test (no published value)
• Acceleration and rotation rate per test (optional)

Higher values mean more tremor. Test-retest ICCs of the log median squared energy were .83–.94, higher on the more affected side, and its correlation with the MDS-UPDRS tremor items was strongest on the more affected side (rest ρ = .71, postural ρ = .50; Lipsmeier et al., 2022). Tremor power correlated with clinical rest (r = .60) and postural (r = .65) tremor ratings in a small sample (n = 14; Kassavetis et al., 2016). Lipsmeier et al. excluded tests with the phone on a table but publish no rule; this task does not flag them.

• In 316 people with early Parkinson's disease, the phone's rest and postural tremor measures were reliable (ICC .83–.94) and related to clinical tremor ratings (Lipsmeier et al., 2022).
• Tremor power measured with a phone held in the hand correlated with clinical ratings of rest and postural tremor (Kassavetis et al., 2016).

• Lipsmeier, Taylor, Postuma et al. (2022), Reliability and validity of the Roche PD Mobile Application for remote monitoring of early Parkinson's disease, Scientific Reports 12:12081 (source of the defaults)
• Lipsmeier, Taylor, Kilchenmann et al. (2018), Evaluation of smartphone-based testing to generate exploratory outcome measures in a phase 1 Parkinson's disease clinical trial, Movement Disorders 33:1287–1297
• Kassavetis, Saifee, Roussos et al. (2016), Developing a tool for remote digital assessment of Parkinson's disease, Movement Disorders Clinical Practice 3:59–64 (tremor power)
• Kostikis, Hristu-Varsakelis, Arnaoutoglou & Kotsavasiloglou (2015), A smartphone-based tool for assessing parkinsonian hand tremor, IEEE J Biomed Health Inform 19:1835–1842

• Static Balance
• Finger Tapping Variability
• Dual-Task Walking